This invention relates generally to gauges and more particularly to water or other liquid thickness gages.
Previous methods and apparatus that can be used to measure water or other liquid thickness include fiber optic sensors, acoustic wave sensors and microwave sensors. These prior art devices are either limited in range, complex, or expensive. A prior art single resistance sensor is a simple and inexpensive device for measuring water thickness. However, its measurements are dependent on water conductivity. Consequently, when the conductivity of the water varies there is an error in the measurements. This makes the single resistance sensor unsuitable for many applications.
It is therefore an object of this invention to modify the water thickness measurements made by single resistance sensors such that the measurements are not dependent on water conductivity.
Another object of this invention is to provide a simple, inexpensive method and apparatus for measuring the thickness of a liquid on a surface that is independent of the liquid conductivity.
Other objects and advantages of this invention will become apparent hereinafter in the specification and drawings.